The Siren Song of Modularity

Product designers and engineers are drawn to the idea of modularity. I am guilty – I find modular product concepts irresistibly compelling.

It seems every few years, a new product or concept comes out that stokes that interest – promising all the benefits of modularity, yet with none of the costs. The most recent high-profile example I’m aware of was PhoneBloks, which eventually became Project Ara within Google.

The concept is quite cool. A fully modular phone, where every element: battery, display, camera, speakers, processor, etc. – is user-removable and replaceable. Enabling you to customize your phone for how you want to use it, personalize it, and easily upgrade to whatever the next cool thing is. Creating the physical equivalent of an “app store” for modules, and opening up a brand new ecosystem for innovation.

This was a fairly radical and novel idea for phones, but modularity is certainly not a novel idea. It shows up all over the place, in different ways.

While I was at IDEO, we worked on the Handspring Visor PDA (not public display of affection – but personal digital assistant, that short-lived product category tech-types bought before smart phones). The Handspring differentiated itself from it’s close cousin, the Palm Pilot, in part by using a modular system called the “Springboard,” which would allow you to plug in all kinds of interesting hardware modules: cameras, extra memory, cellular modems, etc. As technology improved, you would always have access to the latest cool gadget without having to buy a new PDA.

The very non-modular iPhone pretty easily beat the Handspring and other modular mobile devices, relegating them to the kitchen drawer of tech history.

In a different industry, Project Better Place attempted to bring modularity to electric vehicles, by making a swappable battery pack for EVs. So, instead of plugging in and waiting 30 minutes or more to recharge your car, you’d pull into a Better Place swap station, and get a fresh new battery installed by a robot in minutes. As battery technology improved, you would benefit, versus being stuck with that aging, obsolete battery for however long you owned the car.

The fully-integrated, non-replaceable battery of the Tesla Model S, combined with their super charger network pretty easily beat the Better Place vision (although modularity certainly wasn’t the only reason).

Just so you don’t think I’m cherry-picking only product failures to use as examples, there are some great examples where modularity has been successful.

The Personal Computer, in it’s original form, was the ultimate modular product. Swap out graphics boards, memory, power supplies, hard drives, peripherals, as needed. Build your own from a wide range of components and vendors. And, of course, software applications on PCs and other platforms represent the ultimate in product modularity.

I would argue that the PC worked as a modular product because it is really a platform, not a product. It doesn’t do anything on it’s own, without it’s hardware and software modules. And, it’s days as a modular product appear to be numbered, perhaps relegated to a niche of high-performance gamers and hobbyists. The classic desktop PC is giving way to ever more powerful laptops, tablets, and smart phones, most with zero modularity (can’t even replace the battery) – purpose-built, optimized, svelte and sleek, and great at doing what they are designed to do.

Modularity is the go-to for design students and design competitions. It never goes away – concepts for modular housing, modular transportation, modular furniture, modular appliances, modular electronics, etc.. are continually recycled, replayed, reconsidered. Yet, unfortunately, they almost never make it to market.

In most cases (but certainly not all), purpose-built products are going to beat modular products, every time.

Adding modularity to a product has real costs. For physical products, making something removable and replaceable almost always adds size, weight, and cost, and impacts the performance of the product’s core function. There is a reason why Apple does not make the batteries on their products user replaceable – the phone would be thicker and heavier (and would last longer – something consumers might want, but Apple doesn’t). There is a reason why Tesla does not make the batteries on their vehicles user replaceable – the car would be bigger and heavier, and would have more failure modes – there is nothing more tricky to do well than to design a reliable electro-mechanical connector.

And, modularity works best in a diverse, open ecosystem. Those who have tried to build their own closed modular product platforms have typically failed. And getting others to invest in developing modules for your product is not easy.

I’m not suggesting designers stop trying – it is a noble goal. But, beware of the siren song of modularity. Many have tried and failed before you. And, like you, I am still strangely attracted to it…